1. Field
Example embodiments of the present invention may relate to a method of exposing a substrate and an apparatus for performing the method.
2. Description of the Related Art
Generally, to manufacture a semiconductor device a photolithography process is performed to form a photoresist pattern on a semiconductor substrate. The photolithography process includes a coating process, a baking process, an exposing process, a developing process, etc. For example, a photoresist film is formed on the substrate by a coating process. The photoresist film is then hardened by a baking process. Thereafter, exposing and developing processes are performed on the hardened photoresist to transfer a photoresist pattern onto the photoresist film. A photo mask may be used in the exposing process.
The photoresist film formed on the substrate is selectively exposed to light in an exposing process. When light generated by a light source is provided to the photoresist film through the photo mask, an image of patterns formed on the photo mask may be projected onto the photoresist film. However, to achieve high degree of integration of the semiconductor device, an image of a complex pattern is projected onto the photoresist film by using two photo masks and two consecutive exposing processes. For example, a first photo mask is loaded and the photoresist film is exposed to light by using the first photo mask. The first photo mask is then unloaded, and a second photo mask is loaded. Furthermore, the photoresist film is exposed to light by using the second photo mask, and then the second photo mask is unloaded.
In the conventional method, an efficiency of the exposing process may be deteriorated because the two masks are used in two consecutive exposing processes to project an image of one pattern onto the substrate. In addition, the two masks require precise alignment. Precisely aligning images of the first and second photo masks onto the substrate is not an easy task.